Pectinophora gossypiella (Saunders)
The Pink Bollworm
Hosts: It is a serious pest of cotton and also attacks hibiscus, okra, hollyhock and other malvaceous plants.
Damage: In the younger crop larvae bore into tender squares and feed within resulting into drying of the terminal shoots. Later flower buds and bolls are attacked. Infested flower buds fail to open up completely due to webbing by the larva, giving the appearance of a typical rosette bloom. Larvae damage the bolls by tunneling into them, destroying the pulp and lint. Infested bolls open prematurely permitting fungal infection.
Life cycle: Adult is a small moth having wingspan of 10-15 mm, dark brown, with irregular black markings on the fore wing. Hind wing silvery gray with no distinct markings. Both wings are elongated, fringed with long hairs posteriorly and the tip of hind wing is sharply pointed. Fecundity is about 150 eggs/female. Eggs are flattened, pale yellow with striated surface and laid in the night on bracts, buds or flowers, singly or in small groups. Incubation period is 4-6 days. Larvae are pinkish in color with brownish head and 10 mm when full grown. Then it penetrates the lint until it reaches the seed, which also it bores and damages. There are four larval instars and total larval development takes 20-30 days depending on temperature. Larvae overwinter by curling inside cotton seeds and become active again in April. Pupation takes place either in the lint or in debris or under bracts or bark on the plant. Pupal period is 7-10 days and total life cycle is completed in 4-5 weeks.
Distribution: This is a serious pest of cotton in all the cotton-growing areas of the world and particularly severe in the tropics and subtropics of Asia.
Control: Field sanitation is very important. Withering shoots and infested bolls should be dislodged by passing a rope over the plants, then collected and burnt or buried. Destruction of weeds that serve as alternate hosts in the neighboring area helps to reduce population.
Foliar sprays of insecticides at fortnightly interval starting with 10 week old crop kill younger and exposed larvae but the larvae which have bored into the bolls or seeds escape contact with insecticide. The following concentrations of insecticides @ of about 1000 liters per hectare have been found to be effective against this pest: Endrin 0.2%, Malathion 0.1%, Gusathion 0.05%, Carbaryl 0.15%, Cypermethrin, Permethrin or Decamethrin 0.002%.
The following biological control agents help to reduce the population naturally: the egg parasite, Trichogramma acheae, the larval parasite, Bracon sp. And the pupal parasite, Eulopid sp. In addition there is also an anthocorid bug, Triphles tintilus, that feeds on the eggs of this pest.